This is something I’ve been meaning to write for a while, and finally got round to doing. Basically, it’s a simple Thunderbird extension that makes it easier for you to check other folders for new messages. I’ve named it FolderCheck* (rather unimaginatively), and it’s available from the Mozilla Add-ons site sandbox.
The problem is that, at the moment, Thunderbird will only check either the inbox or every folder for messages (for all accounts). This is pretty useless for me, as I only get new email in my inbox for some accounts, and get my email server-sorted into different folders for other accounts. This means that if I want to tell Thunderbird to check a specific folder for messages, I have to right-click the folder, choose “Properties”, check “Check this folder for new messages”, then click OK. And do it all over again for the next folder. And the next. This quickly gets irritating!
My extension adds a new “Check for new items” item to the context menu for each folder (except Inbox and some other special folders) that allows you to quickly see whether a folder is checked for new messages, and to quickly and easily toggle that setting. Now I just have to right-click each folder and hit “h” to toggle the setting.
Coming soon (when I get round to it): a dedicated window to make multiple folder selection easy. My current thought is a list of folders with a filter box and “(De)Select All Visible Folders” buttons.
* Note: currently requires a free Mozilla Developer account, as it’s not yet a public extension.